Spinal alignment and securement

ABSTRACT

A surgical connection device for a spine is disclosed including a stabilization member, compression arms and traction arms, the device being used in conjunction with first anchor points fixed to vertebrae at a first lateral side of the spine and second anchor points fixed to vertebrae at a second lateral side of the spine. A first spinal rod may be attached to the first anchor points and a second spinal rod may be attached to the second anchor points. The compression arms connect the stabilization member to the first and second anchor points or rods and bear compressive forces. The traction arms connect the stabilization member to the first and o second anchor points or rods and bear tensile forces. Application of both tensile and compressive forces via the device may serve to straighten, change a direction of bending or increase a degree of bending of the rods and/or spine. The use of the traction arms may also provide for a more flexible construct.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Australian ProvisionalPatent Application No 2014904032 filed on 9 Oct. 2014 and AustralianProvisional Patent Application No 2014904536 filed on 10 Nov. 2014, thecontents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to posterior spinal surgery and devicesused in spinal surgery.

BACKGROUND

Posterior spinal surgery, including spinal fixation surgery, is a commonprocedure used in the treatment of spinal conditions such asspondylolisthesis, scoliosis, spinal trauma, spinal tumor and otherspinal deformities or degenerative conditions.

Typically, the surgery involves inserting pedicle screws into vertebraeto establish anchor points. A stabilizing rod may then be securedbetween several of the anchor points to restrict or limit relativemovement between vertebrae. This process can be carried out on oppositesides of the spine, such as to secure two stabilizing rods to the spine.To further stabilize the spine, a connection device can be appliedbetween the two stabilizing rods or between the anchor points (e.g. whenno stabilizing rods are used), maintaining the position of the rodsand/or anchor points relative to each other. When the posterior spinalfixation surgery is completed, spinal fusion may be carried out.

An example of a connection device applied between stabilizing rods isdisclosed in patent publication US 2012/0095510 A1.

Any discussion of documents, acts, materials, devices, articles or thelike which has been included in the present specification is not to betaken as an admission that any or all of these matters form part of theprior art base or were common general knowledge in the field relevant tothe present disclosure as it existed before the priority date of eachclaim of this application.

SUMMARY

According to one aspect, the present disclosure provides a surgicalconnection device for a spine, a plurality of first anchor points beingfixed to vertebrae at a first lateral side of the spine, a plurality ofsecond anchor points being fixed to vertebrae at a second lateral sideof the spine, a first spinal rod being attached to the plurality offirst anchor points and a second spinal rod being attached to theplurality of second anchor points, the device comprising:

a stabilization member;

a plurality of compression arms to connect the stabilization member tothe first and second rods and bear compressive forces between thestabilization member and the first and second rods; and

a plurality of traction arms to connect the stabilization member to thefirst and second rods and bear tensile forces between the stabilizationmember and the first and second rods.

According to another aspect, the present disclosure provides a surgicalconnection device for a spine, a plurality of first anchor points beingfixed to vertebrae at a first lateral side of the spine and a pluralityof second anchor points being fixed to vertebrae at a second lateralside of the spine, the device comprising:

a stabilization member;

a plurality of compression arms to connect the stabilization member toat least one first anchor point and at least one second anchor point andbear compressive forces between the stabilization member and the firstand second anchor points; and

a plurality of traction arms to connect the stabilization member to atleast one first anchor point and at least one second anchor point andbear tensile forces between the stabilization member and the first andsecond anchor points.

According to another aspect, the present disclosure provides a surgicalmethod for a spine, a plurality of first anchor points being fixed tovertebrae at a first lateral side of the spine, a plurality of secondanchor points being fixed to vertebrae at a second lateral side of thespine, a. first spinal rod being attached to the plurality of firstanchor points and a second spinal rod being attached to the plurality ofsecond anchor points, the method comprising:

connecting a stabilization member of a surgical connection device to thefirst and second rods using a plurality of compression arms that areconfigured to bear compressive forces between the stabilization memberand the rods; and

connecting a plurality of traction arms of the surgical connectiondevice between the stabilization member and the first and second rods,the traction arms being configured to bear tensile forces between thestabilization member and the rods.

According to another aspect, the present disclosure provides a surgicalmethod for a spine, a plurality of first anchor points being fixed tovertebrae at a first lateral side of the spine and a plurality of secondanchor points being fixed to vertebrae at a second lateral side of thespine, the method comprising:

connecting a stabilization member of a surgical connection device to atleast one first anchor point and at least one second anchor point usinga plurality of compression arms that are configured to bear compressiveforces between the stabilization member and the first and second anchorpoints; and

connecting a plurality of traction arms of the surgical connectiondevice between the stabilization member and at least one first anchorpoint and at least one second anchor point, the traction arms beingconfigured to bear tensile forces between the stabilization member andthe first and second anchor points.

The stabilization member may be elongate. The direction of elongation ofthe stabilization member may be substantially parallel to the spinalaxis. The stabilization member may be rod-like. The stabilization membermay comprise one or more rods. When first and second rods are providedattached to anchor points, the stabilization member may provide a thirdspinal rod, or third and fourth spinal rods, that is/are substantiallyparallel to the first and second rods. The stabilization member mayextend across multiple vertebrae, e.g. at least 2 vertebrae, at least 3vertebrae or at least 4 vertebrae. Nevertheless, the stabilizationmember may take a variety of different forms.

The anchor points may be bone screws or other surgical devices thatprovide means for fixation to vertebrae of the spine. Bone screws mayinclude pedicle screws, for example.

The stabilization member may provide for stiffening of the rods whenconnected to the rods or provide for stabilizing of the anchor points.The stabilization member may provide an anchor device, relative to whichcompressive and tensile forces can be applied to the rods and/or anchorpoints, e.g., such as to force a bend in the rods or to straighten therods and/or to force relative movement of the anchor points and theattached vertebrae. Additionally or alternatively, the stabilizationmember may provide for stabilization as part of a motion preservationsystem.

To aid understanding of the configuration of the connection device,various features of the connection device are described and/ordistinguished with reference to an anatomical reference system,including anatomical directions and anatomical planes, for example, Ingeneral, anatomical references are indicative of the position andorientation of features of the device when the device is in a deployed,implanted state. For example, where superior and inferior elements ofthe device are described, it can be expected that the superior elementwill be located closer to the head of the recipient and the inferiorelement will be located closer to the feet of the recipient, when thedevice is in its deployed, implanted state.

The stabilization member may comprise a superior end and an inferiorend. The direction of elongation of the stabilization member may extendbetween the superior and inferior ends. The stabilization member mayinclude walls that extend on opposite sides of the stabilization memberbetween the superior and inferior ends.

The plurality of compression arms may comprise at least a firstcompression arm to connect between the stabilization member and thefirst rod or to connect between the stabilization member and a firstanchor point, and at least a second compression arm to connect betweenthe stabilization member and the second rod or to connect between thestabilization member and a second anchor point. The first and secondcompression arms may each have a first end connected to thestabilization member and a second end to connect to the respectiverod/anchor point. The first compression arm may be connected to thestabilization member at a position that is on a substantially oppositeside of the stabilization member to a position at which the secondcompression arm is connected to the stabilization member. For example,the first end of the first compression arm may be connected to a firstlateral wall of the stabilization member and the first end of the secondcompression arm may be connected to an opposite second lateral wall ofthe stabilization member.

The plurality of traction arms may comprise at least two first tractionarms to connect between the stabilization member and the first rod/firstanchor points and at least two second traction arms to connect betweenthe stabilization member and the second rod/second anchor points. Eachof the first and second traction arms may have a first end to connect tothe stabilization member and a second end to connect to the respectiverod/anchor point. The first traction arms may connect to thestabilization member at a position that is on a substantially oppositeside of the stabilization member to a position at which the secondtraction arms connect to the stabilization member. For example, thefirst ends of the first traction arms may connect to the first lateralwall of the stabilization member and the first ends of the secondtraction arms may connect to the second lateral wall of thestabilization member.

The two first traction arms may connect to the first rod at positions oneither side of the position at which the fiat compression arm connectsto the fiat rod. For example, one of the two first traction arms mayconnect to the first rod at a position that is superior to the positionat which the first compression arm connects to the first rod, and theother of the two first traction arms may connect to the first rod at aposition that is inferior to the position at which the first compressionarm connects to the first rod.

The two first traction arms may therefore pull superior and inferiorportions of the first rod towards the stabilization member while thefirst compression member pushes an intermediate portion of the firstrod, between the superior and inferior portions, away from thestabilization member (e.g., to maintain the intermediate portion of thefirst rod at a fixed distance from the stabilization member). Theapplication of both tensile and compressive forces may serve tostraighten the first rod, change a direction of bending of the first rodor increase a degree of bending of the first rod.

Where the plurality of traction arms are connected directly to theanchor points rather than rods, the two first traction arms may connectto two respective first anchor points located either side of a firstanchor point to which the first compression arm is connected. Forexample, one of the two first traction arms may connect to a firstanchor point that is superior to the first anchor point to which thefirst compression arm is connected, and the other of the two firsttraction arms may connect to a first anchor point at a position that isinferior to the first anchor point to which the first compression arm isconnected.

Since the first anchor points can be connected to different vertebrae,the two first traction arms may therefore pull superior and inferiorvertebrae towards the stabilization member while the first compressionmember pushes an intermediate vertebrae, between the superior andinferior vertebrae, away from the stabilization member (e.g., tomaintain the intermediate vertebrae at a fixed distance from thestabilization member). The application of both tensile and compressiveforces may serve to straighten the spine, change a direction of bendingof the spine or increase a degree of bending of the spine. While similaradjustment is described in preceding paragraphs in relation to the firstrod, since the first rod is connected to anchor points which can beconnected to vertebrae, the adjustment of the first rod may also resultin the same spinal adjustment.

Similarly, the two second traction arms may connect to the second rod atpositions on either side of the position at which the second compressionarm connects to the second rod. For example, one of the two secondtraction arms may connect to the second rod at a position that issuperior to the position at which the second compression arm connects tothe second rod, and the other of the two second traction arms mayconnect to the second rod at a. position that is inferior to theposition at which the second compression arm connects to the second rod.

The two second traction arms may therefore pull superior and inferiorportions of the second rod towards the stabilization member while thesecond compression member pushes an intermediate portion of the secondrod, between the superior and inferior portions, away from thestabilization member (e.g., to maintain the intermediate portion of thesecond rod at a fixed distance from the stabilization member). Theapplication of both tensile and compressive forces may serve tostraighten the second rod, change a direction of bending of the secondrod or increase a degree of bending of the second rod.

Where the plurality of traction arms are connected directly to theanchor points rather than two first and second rods, the two secondtraction arms may connect to two respective second anchor points locatedeither side of a second anchor point to which the second compression armis connected. For example, one of the two second traction arms mayconnect to a second anchor point that is superior to the second anchorpoint to which the second compression arm is connected, and the other ofthe two second traction arms may connect to a second anchor point at aposition that is inferior to the second anchor point to which the secondcompression arm is connected.

Since the second anchor points can be connected to different vertebrae,the two second traction arms may therefore pull superior and inferiorvertebrae towards the stabilization member while the second compressionmember pushes an intermediate vertebrae, between the superior andinferior vertebrae, away from the stabilization member (e.g., tomaintain the intermediate vertebrae at a fixed distance from thestabilization member). The application of both tensile and compressiveforces may serve to straighten the spine, change a direction of bendingof the spine or increase a degree of bending of the spine. While similaradjustment is described in preceding paragraphs in relation to the rod,since the second rod is connected to anchor points which can beconnected to vertebra, the adjustment of the second rod may also resultin the same spinal adjustment.

The above described arrangement may draw the rods or spine into lordosisor further lordosis. Where a kyphotic deformity or correction is desiredthe positions of the compression and traction arms may be reversed. Theconnection positions of the compression arms to the stabilization memberand/or to the rods may be variable along the axes of elongation of thestabilization member and rods. Accordingly, the compression arms may berepositioned along the direction of the spinal axis, to providecompression at a desired point and/or to avoid interfering with theanatomical features or other apparatus, such as pedicle screws. Thevariability in positioning may also enable a torsional force on thespinal column to be induced or resisted. This may be achieved throughlocating the compression arms, located at opposite sides of the spine,at different positions along the spinal axis.

Similarly, the connection positions of the traction arms to thestabilization member and/or to the rods may be variable along the axesof elongation of the stabilization member and rods. Accordingly, thetraction arms may be repositioned along the direction of the spinalaxis, to provide tension at a desired point and/or to avoid interferingwith the anatomical features or other apparatus, such as pedicle screws.The variability in positioning may also enable a torsional force on thespinal column to be induced or resisted. This may be achieved throughlocating the traction arms, located at opposite sides of the spine, atdifferent positions along the spinal axis.

Due to the differing natures of the forces transferred through thecompression arms and the traction arms, the compression arms may beconfigured differently from the traction arms. For example, thecompression arms may be rigid elements that can withstand relativelyhigh compression forces without substantially changing shape, e.g.,without buckling . The compression arms may be more rigid than thetraction arms. The traction arms may be flexible elements. The tractionarms may be more flexible than the compression arms but may withstandconsiderable tensile forces without stretching. In one embodiment, thetraction arms are provided by wires or relatively narrow rods, whereasthe compression arms are provided by rigid arms that have a width and/ordepth that is larger than that of the traction arms. By providingflexible traction arms, e.g., that bend under compression, the surgicalconnection device may have regions of enhanced flexibility. The tractionarms may provide the surgical connection device with spring-likequalities and may enable a degree of “bounce” to take place during itsuse, in conjunction with the adjacent anatomical structures. This mayprovide stress protection to the apparatus and adjacent anatomicalstructures and provide for increased motion preservation of the spine.For example, when the traction arms are provided adjacent inferiorand/or superior ends of the surgical connection device, the tractionarms may provide a flexible transition between a region of the spinethat is stabilized by the connection device and non-stabilized adjacentregion(s) of the spine. This may reduce the likelihood of damage,breakage and/or “adjacent segment degeneration” occurring tonon-stabilised adjacent regions of the spine, e.g., as a result of forcetransfer through the connection device and/or stabilized region of thespine, The degree of flexibility of the traction arms, or other arms orconnecters disclosed herein, may be selected or un to achieve thedesired degrees of flexibility or rigidity.

Due to the differing natures of the forces transferred by thecompression arms and the traction arms, the manner in which thecompression arms connect to the stabilization member and/or rods and/oranchor points may be different to the manner in which the traction armsconnect to the stabilization member and/or rods and/or anchor points.The connectors may be connected to the stabilizing member, rods andanchor points using a variety of different techniques.

One or more of the compression and traction arms may extend from thestabilization member in an anterior-lateral direction. Accordingly, whenconnected to the rods or anchor points, the stabilization member may belocated medially and posteriorly of the rods and/or anchor points.Depending on the size of the spine, the stabilization member may bepositioned about 5-25 mm posteriorly of a plane extending through therods or anchor points (e.g. extending through heads of bone screwsacting as anchor points) or otherwise.

The stabilization member may be offset from a central axis of the spine,such as to locate laterally of the tips of the spinous processes.Alternatively, when a portion of the spinal lamina and the spinousprocesses is removed during a laminectomy, the stabilization member maylocate along the central axis at a position at or adjacent to theexterior extents of the tips of the spinous processes prior to removalthereof. As another alternative, the stabilization member may comprisetwo elongate members that each extend along the spine and which arespaced apart in a medial-lateral direction such as to provide a gap toaccommodate tips of the spinous processes. The two elongate members maybe two rods, for example, which extend substantially parallel to eachother on opposite sides of the spinous processes. One or moreconnectors, e.g. bolts, may connect the elongate members together. Theone or more connectors may extend through one or more interspinousspaces between adjacent spinous processes, through one or moreinterspinous ligaments and/or through one or more spinous processes orany other structure located between the elongate members.

According to one aspect, the present disclosure provides a surgicalconnection device for a spine, a plurality of first anchor points beingfixed to vertebrae at a first lateral side of the spine, a plurality ofsecond anchor points being fixed to vertebrae at a second lateral sideof the spine, a first spinal rod being attached to the plurality offirst anchor points and a second spinal rod being attached to theplurality of second anchor points, the device comprising:

an elongate stabilization member; and

a plurality of arms to connect the stabilization member to the first andsecond rods;

wherein the device is configured such that, when the stabilizationmember is connected to the first and second rods by the plurality ofarms, the direction of elongation of the stabilization member liessubstantially parallel to the axis of the spine, or other desired axis,and the stabilization member locates:

(a) posteriorly of the rods at a position that is not substantially moreposterior than the posterior extents of the tips of spinous processes ofthe vertebrae to which the anchor points are fixed; or

(b) when one or more spinous processes of the vertebrae to which theanchor points are fixed have been removed, posteriorly of the rods at aposition that is not substantially more posterior than the positions atwhich the posterior extents of the tips of the spinous processes of thevertebrae to which the anchor points are fixed were located prior toremoval.

According to another aspect, the present disclosure provides a surgicalconnection device for a spine, a plurality of first anchor points beingfixed to vertebrae at a first lateral side of the spine and a pluralityof second anchor points being fixed to vertebrae at a second lateralside of the spine, the device comprising:

an elongate stabilization member; and

a plurality of arms to connect the stabilization member to the first andsecond anchor points;

wherein the device is configured such that, when the stabilizationmember is connected to the first and second anchor points by theplurality of arms, the direction of elongation of the stabilizationmember lies substantially parallel to the axis of the spine, or otherdesired axis, and the stabilization member locates:

(a) posteriorly of the anchor points at a position that is notsubstantially more posterior than the posterior extents of the tips ofspinous processes of the vertebrae to which the anchor points are fixed;or

(b) when one or more spinous processes of the vertebrae to which theanchor points are fixed have been removed, posteriorly of the anchorpoints at a position that is not substantially more posterior than thepositions at which the posterior extents of the tips of the spinousprocesses to which the anchor points are fixed were located prior toremoval.

According to another aspect, the present disclosure provides a surgicalmethod for a spine, a plurality of first anchor points being fixed tovertebrae at a first lateral side of the spine, a plurality of secondanchor points being fixed to vertebrae at a second lateral side of thespine, a first spinal rod being attached to the plurality of firstanchor points and a second spinal rod being attached to the plurality ofsecond anchor points, the method comprising:

connecting a stabilization member of a surgical connection device to thefirst and second rods using a plurality of arms, wherein the connectinglocates the stabilization member:

(a) posteriorly of the rods at a position that is not substantially moreposterior than the posterior extents of the tips of spinous processes ofthe vertebrae to which the anchor points are fixed; or

(b) when one or more spinous processes of the vertebrae to which theanchor points are fixed have been removed, posteriorly of the rods at aposition that is not substantially more posterior than the positions atwhich the posterior extents of the tips of the spinous processes of thevertebrae to which the anchor points are fixed were located prior toremoval.

According to another aspect, the present disclosure provides a surgicalmethod for a spine, a plurality of first anchor points being fixed tovertebrae at a first lateral side of the spine and a plurality of secondanchor points being fixed to vertebrae at a second lateral side of thespine, the method comprising:

connecting a stabilization member of a surgical connection device to thefirst and second anchor points using a plurality arms, wherein theconnecting locates the stabilization member:

(a) posteriorly of the anchor points at a position that is notsubstantially more posterior than the posterior extents of the tips ofspinous processes of the vertebrae to which the anchor points are fixed;or

(b) when one or more spinous processes of the vertebrae to which theanchor points are fixed have been removed, posteriorly of the anchorpoints at a position that is not substantially more posterior than thepositions at which the posterior extents of the tips of the spinousprocesses of the vertebrae to which the anchor points are fixed werelocated prior to removal.

In one embodiment, the stabilizing member may be located substantiallyadjacent or level with the tips of the spinous processes. Depending onthe size of the spine, the stabilization member may be positioned about5-25 mm or about 5-35 mm or about 10-35 mm posteriorly of a planeextending through the rods or anchor points (e.g. through heads of bonescrews acting as anchor points).

The plurality of arms may comprise both compression arms and tractionarms as described with respect to the preceding aspect.

In the above aspects, devices and methods are described in which armsare connected either to rods attached to anchor points or to the anchorpoints themselves. Yet further aspects can employ a mix of theseconnection approaches. For example, one or more rods may be providedthat are not connected to all of the relevant anchor points, andtherefore one or more of the arms may be connected to rod(s) and one ormore arms may be connected to anchor point(s). For example, at least onecompression arm may be connected to rod(s) and at least one tractionarms may be connected to anchor point(s). Anchor points to which thearms are connected directly may include only the most superior andinferior anchor points, for example. This may provide for dynamicstabilisation with increased resilient flexibility, e.g. for thepurposes of motion preservation. Nevertheless, direct connection mayalso apply to a mid-section of anchor points or any other combination.

According to one aspect, the present disclosure provides a surgicalconnection device for a spine, the device comprising:

a stabilization member;

a plurality of arms to connect the stabilization member to first andsecond spinal rods on first and second lateral sides of a first regionof the spine; and

a plurality of arms to connect the stabilization member to first andsecond anchor points on first and second lateral sides of a secondregion of the spine different from the first region of the spine.

Anchor points are not to be limited to the lateral aspects of the spine.Midline anchor points as well as off axis anchor points may in beincorporated with any or all aspects of this disclosure.

In any of the aspects, where compression and traction arms are provided,one or more of the compression and traction arms may extend from thestabilization member in an anterior-lateral-superior direction and/orone or more of the compression and traction arms may extend from thestabilization member in an anterior-lateral-inferior direction.

In one embodiment:

the first compression arm extends from the stabilization member in ananterior-lateral direction towards the first rod or one of the firstanchor points;

one of the first traction arms extends from the stabilization member inan anterior-lateral- superior direction from the stabilization membertowards the first rod or one of the first anchor points;

another of the first traction arms extends from the stabilization memberin an anterior-lateral-inferior direction from the stabilization membertowards the first rod or one of the first anchor points;

the second compression arm extends from the stabilization member in ananterior-lateral direction towards the second rod or one of the secondanchor points;

one of the second traction arms extends from the stabilization member inan anterior-lateral-superior direction from the stabilization membertowards the second rod or one of the second anchor points;

another of the second traction arms extends from the stabilizationmember in an anterior-lateral-inferior direction from the stabilizationmember towards the second rod or one of the second anchor points.

In one embodiment, the stabilization member provides a single, centralor off-axis posteriorly located rod with anchor points being connectedsolely to the stabilization member by the compression and traction arms.This embodiment may provide improved superior surgical access to thelateral nerve roots and bone allowing ease of surgical resection andbone grafting.

Connection devices disclosed herein may facilitate controlledapplication of forces to vertebrae for the purpose of re-alignment ofthe vertebrae. The forces may be transmitted to vertebrae by the anchorpoints, e.g., pedicle screws, optionally via rods, without pulling outthe screws or breaking the pedicle. There may be provided reinforcing ofthe anchor point construct in all planes to resist or modulate deformingloads applied to the construct during weight bearing, e.g., prior to thefusion of the spine. The connection devices may assist in theapplication of forces to adjacent segments of the construct, e.g.sections defined between immediately adjacent anchor points or between aplurality of anchor points inferior to and/or superior to a section ofthe vertebral column that is to be fused. The connection devices maybuffer against undesirable distortion at an end of the construct forexample, while maintaining e.g., a lordotic or kyphotic bias, forexample. Forces may be applied by the connection devices off-spinal-axiswhere a slight enduring scoliosis is encountered. The connection devicesmay provide for a triangular-cross section of reinforcement and mayprovide means of shaping rods and/or the vertebral column in situ aswell as preventing deformation thereof due to anatomic loads and anyexisting deformity and scar tissue.

The stabilization member, e.g. due to its posterior location relative tothe rods or anchor points, may provide a guide or reattachment surfacefor spinal musculature and fascia after surgery, allowing better woundclosure and care. The stabilization member may allow the musculature tolie in a more anatomic post-operative plane and hence may decreasepost-operative pain/stiffness. It may improve post-operative muscularpower and function and provide for more efficient energy utilization ofthese muscles to residual un-instrumented levels. Additionally thestabilization member and/or other parts of the device, may be used as asupport for further dynamic connectors between instrumented vertebraeallowing controlled yet flexible deformity correction above and belowthe level of fusion. Furthermore, the stabilization member and/or otherparts of the device may act as a scaffold for increased bone graftattachment points and hence greater fusion mass. Still further, thestabilization member and its connected arms may act to protect the duralsac post-operatively and during any subsequent surgery, in the lattercase by defining the tissue plane of the spinal canal and the containeddural sac. Furthermore, the stabilization member may act as a scaffoldfor an anti-adhesion polymer, (or biomer) layer, to protect the duralsac.

Surgical connection devices according to the present disclosure maycomprise a support that supports the posteriorly-located stabilizationmember from an anterior side of the stabilization member. The supportmay function as a prop for the stabilization member. The support maycomprise a first connector that connects between opposite lateral sidesof the spine and a second connector that connects the first connector tothe stabilization member.

The support may be adapted for use with a variety of different surgicalconnection devices. For example, in one embodiment a surgical connectiondevice may comprise a rod that extends between opposite lateral sides ofthe spine and which is arced in a posterior direction. The support mayprovide support for the rod, e.g., at most posteriorly located portionof the rod or otherwise.

Thus, according to one aspect, there is provided a support for asurgical stabilization member, the support comprising:

a first connector adapted to connect between opposite lateral sides ofthe spine; and

a second connector adapted to connect the first connector to thestabilization member.

The first connector may connect between first and second rods onopposite lateral sides of the spine or between first and second anchorpoints on opposite lateral sides of the spine. The first and secondconnectors may be integrated or may be separate pieces that areconnected together, e.g., during surgery. The first and secondconnectors may each be elongate, with their directions of elongationextending substantially perpendicularly to each other. The firstconnector may extend in a medial-lateral direction, whereas the secondconnector may extend in an anterior-posterior direction. The firstconnector may be connected to the second connector at a centre of thesecond connector or otherwise. The support may be a T-shaped support,The first connector may be a cross-bar and the second connector may be abuttress.

As indicated, surgical connection devices of the present disclosure mayprovide stabilization while exhibiting a motion preserving function. Ingeneral, where bone fusion is carried out, articulation of the spine issubstantially eliminated. The surgical connection devices may be used asan adjunct to fusion, e.g., to provide motion preserving support tovertebrae located to one or both sides of a section of fused vertebrae,or to be used in place of a spinal fusion. In either case, the surgicalconnection device may provide for a stabilisation region of the spinewhile enabling motion preservation at and/or adjacent the stabilisedregion.

The surgical connection device may include means for adjusting stiffnessat different vertebral levels as required. The stiffness of thestabilizing member and/or the stiffness of arms connecting thestabilizing member to rods or anchor points may be adjusted depending onthe degree of motion preservation required and the location of therequired motion preservation. The stabilization member and/or arms mayvary in stiffness through material selection, diameters and/or shapeincluding sinuosity, e.g. flexible s-bends. The stabilization memberand/or arms may have varying flexibility across different planes. Forexample, they may have omni-directional flexibility, bi-directionalflexibility, or uni-directional flexibility. The stabilization memberand/or arms with omni-direction flexibility may have uniform flexibilityin every plane or different flexibility in different planes. Thestabilization member and/or arms may be straight or may be bent.

In one embodiment, arms are provided with elements such as resorbablecollars that serve to stiffen the arms. The stiffening effect of theresorbable elements gradually reduces as they are resorbed over time,resulting in a progressive increasing in the flexibility of the arms.

Greater motion preservation using the connection device may be achievedthrough connection of the stabilization member directly to anchorpoints, rather than rods connected to the anchor points. For example, afirst portion of the stabilization member may be connected using armsdirectly to first and/or second rods fixed to a first spinal portion,e.g., a fused vertebral section having three fused vertebrae orotherwise. However, another portion or portions of the stabilizationmember may be connected using arms directly to anchor points fixed at asecond spinal portion, e.g. at non-fused section(s) of vertebrae,located superiorly and/or anteriorly to the first spinal section. In analternative example, the stabilization member may be connected directlyto anchor points only, and no first or second rods may be employed.Nevertheless, the arms connecting the stabilization member to anon-fused portion may have greater flexibility than the arms connectingthe stabilization member to a fused section.

Use of stiffer arms and/or use of first or second rods at a fusedportion of the spine may provide greater stability to the overallconstruct without providing any adverse effect to motion preservation atnon-fused sections. More flexible arms connected to anchor points atnon-fused sections may provide motion preserving stabilisation whiledecreasing the tendency for degeneration at those different vertebrallevels.

In one aspect, the surgical connection device is adapted to stabilize amobile disc replacement of a spine. The surgical connection device mayprovide motion preserving posterior support to the disc replacement.

In another aspect, the surgical connection device is adapted tostabilize a lateral facet joint of a spine. The surgical connectiondevice may provide motion preserving posterior support to the lateralfacet joint.

In one aspect, the present disclosure provides a surgical connectiondevice adapted to stabilize a lateral facet joint of a spine betweenfirst and second vertebrae, comprising:

an elongate stabilization member configured to locate posteriorly of thespine such that the direction of elongation of the stabilization memberis substantially parallel to the spinal axis;

at least a pair of first arms adapted to connect between thestabilization member and anchor points of the first vertebra; and

at least a pair of second arms adapted to connect between thestabilization member and anchor points of the second vertebra.

In any aspects disclosed herein, the surgical connection device maycontrol each plane of movement individually, e.g. by adjusting thestiffness and positioning of each arm to provide desired dampening offorces. The stiffness may be “tuned” to a desired level for each planeof movement. For example, the connection device may provide increasedstiffness/stabilisation in one plane, e.g., a plane that preventsspondylolisthesis, while providing lower stiffness/stabilisation inother planes, e.g. planes that permit flexion and extension.

In one aspect, the present disclosure provides a surgical connectiondevice for a spine, comprising:

an elongate stabilization member;

at least one anchor connected to a first portion of the elongatestabilization member and adapted to substantially fix the position ofthe stabilization member relative to the first portion of the spine,

at least a first control arm connected to a second portion of theelongate stabilization member and adapted to control a movement of asecond portion of the spine relative to the stabilization member.

In another aspect, the present disclosure provides a surgical method fora spine, the method comprising:

fixing the position of an elongate stabilization member relative to afirst portion of a spine using at least one anchor connected between afirst portion of the stabilization member and the first portion of thespine,

controlling a movement of a second portion of the spine relative to thestabilization member using at least a first control arm connectedbetween a second portion of the stabilization member and the secondportion of the spine.

The anchor may connect the first stabilization member to the spine suchthat the stabilization member extends along the spine, e.g. in adirection substantially parallel to the spinal axis. At least the secondportion of the stabilization member may locate at a position that ismedial to a first lateral edge of a vertebra or vertebrae at the secondportion of the spine. The first control arm may project outwardly fromthe second portion of the stabilization member in a direction towardsthe first lateral edge of the vertebra or vertebrae.

The at least one anchor may comprise one or more arms adapted tosubstantially fix the position of stabilization member relative to thefirst portion of the spine. The anchor may comprise arms as described inpreceding aspects, e.g. compression arms and/or traction arms. In oneembodiment, the first portion of the spine comprises fused vertebrae.

The first control arm, while connected to the second portion of thespine, controls a movement of the second portion of the spine relativeto the stabilization member. In this regard, the first control arm whenconnected between the second portion of the stabilization member and thesecond portion of the spine allows relative movement between secondportion of the spine and the stabilization member, in a controlledmanner.

The first control arm may be rotatable relative to the second portion ofthe stabilization member and/or the second portion of the spine such asto control the movement of the second portion of the spine. Rotation maybe achieved through the provision of an articulated joint (e.g. a hingeor pivot) between the first control arm and the second portion of thestabilization member and/or between the first control arm and the secondportion of the spine.

The first control arm may be substantially rigid such as to maintain afixed length while permitting movement between the second portion of thespine and the stabilization member. Alternatively, the first control armmay be flexible. In some instances, bending of the flexible firstcontrol arm may provide for the control of movement of the secondportion of the spine in addition to or as an alternative to employingarticulated joints.

In one embodiment, the surgical connection device comprises at least asecond control arm in addition to the first control arm. The secondcontrol arm may be connected to the second portion of the elongatestabilization member and adapted to control movement of the secondportion of the spine relative to the stabilization member.

The second control arm may be rotatable relative to the second portionof the stabilization member and/or the second portion of the spine suchas to control the movement of the second portion of the spine. Rotationmay be achieved through the provision of an articulated joint (e.g. ahinge or pivot) between the second control arm and the second portion ofthe stabilization member and/or between the second control arm and thesecond portion of the spine.

The second control arm may be substantially rigid such as to maintain afixed length while permitting relative movement between the secondportion of the spine and the stabilization member. Alternatively, thesecond control arm may be flexible. In some instances, bending of theflexible second control arm may provide for the control of movement ofthe second portion of the spine in addition to or as an alternative toemploying articulated joints.

Thus, the second control arm may be configured similarly to the firstcontrol arm. However, the second control arm may be project from thestabilization member in a substantially opposite direction from thefirst control arm.

As discussed above, the second portion of the stabilization member maylocate at a position that is medial to a first lateral edge of avertebra or vertebrae at the second portion of the spine. Additionally,the second portion of the stabilization member may locate at a positionthat is medial to a second lateral edge of the vertebra or vertebrae atthe second portion of the spine, the second lateral edge being oppositeto the first lateral edge. Thus, the second portion of the stabilizationmember may locate centrally between first and second opposite lateraledges of the spine. The first control arm may project outwardly from thesecond portion of the stabilization member in a direction towards thefirst lateral edge and the second control arm may project outwardly fromthe second portion of the stabilization member in a direction towardsthe second lateral edge.

One of the first and second control arms may project in asuperior-lateral direction from the second portion of the stabilizationmember and the other of the first and second control arms may projectionin an inferior-lateral direction from the second portion of thestabilization member.

The second portion of the spine may comprise a single vertebra ormultiple vertebrae, which vertebra or vertebrae may be located at adifferent position along the spine from the first portion of the spine.The first and control arms may connect to the same vertebra or todifferent vertebrae.

The connection device may be used in conjunction with one or more rodsand/or anchor points. For example, a plurality of first anchor pointsmay be fixed to vertebrae of the spine at a first lateral side of thespine, a plurality of second anchor points being fixed to vertebrae at asecond lateral side of the spine. A first spinal rod may be attached tothe plurality of first anchor points and/or a second spinal rod may beattached to the plurality of second anchor points. The anchor and/orcontrol arms may be connected to the spine through connecting to thefirst and second anchor points and/or first and second rods. In someembodiments, the stabilization member may extend over the entire lengthof instrumentation secured to the spine. While there may be sections ofthe spine which include e.g. first and/or second rods as describedabove, the stabilization member may be the primary guiding element forderogation and straightening of the vertebral column.

By providing at least a first control arm, or at least first and secondcontrol arms, which arm(s) control movement of the second portion of thespine relative to the stabilization member, the surgical connectiondevice may provide for re-alignment of the spine. Where a recipient ofthe surgical connection device is a child, for example, general movementof the second portion of the spine may occur as a result of growth ofthe spine post-implantation. The growth may be such as to move thesecond portion of the spine in a direction away from the first portionof the spine. However, by connecting the first control arm to the secondportion of the spine, the direction of growth at the second portion ofthe spine may be controlled by the surgical connection device. Forexample, the control arm(s) may each be movable in a respective singleplane. Relative lengthening of the spinal column may force the arms torotate through an arc in the respective plane. The orientation of eachplane can be selected to drive a desired correction of the tilt androtation of the spine. Assisting in this process is the anchoring of thestabilization member to a. different, first portion of the spine. Insome embodiments, the stabilization member may be anchored to multipleportions of the spine, e.g. different sections of fused vertebrae,providing for intermittent anchoring of the stabilization member alongthe surgical connection device. In some embodiments, the intermittentlyanchored portions of the stabilization member may be interleaved withportions of the stabilization member that are rotatably connected to thespine. In general, the connection device may anchor/fix at one or morevertebral levels and provide for controlled rotation movement at one ormore other vertebral levels.

The surgical connection device, while not restricting growth of thespine, may therefore force a straightening or other type of shapeadjustment of the spine during growth of the spine. This may beparticularly advantageous to treat scoliosis of the spine in children,although the connection device is not necessarily limited to such use.By taking the approach disclosed, growth of the spinal column may not beretarded, the need for re-operation to allow growth may be obviated orat least reduced, and correction of the spine can be achievedpost-operatively and in a gradual fashion.

According to the present disclosure, one or more of the above aspectsmay be combined with one or more of the other above aspects.Furthermore, any of the above aspects or combination of aspects may becombined with any of the optional features discussed herein.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure are now described by way ofexample only with reference to the accompanying drawings, in which:

FIG. 1a shows a perspective view of a surgical connection deviceaccording to an embodiment of the present disclosure;

FIG. 1b shows a perspective view of the surgical connection device ofFIG. 1a connected to first and second rods;

FIG. 1c shows a perspective view of the surgical connection device ofFIG. 1b with traction arms;

FIG. 2a shows a lateral view of the surgical connection device of FIG.1b connected to first and second rods, the rods being anchored tovertebrae via pedicle screws;

FIG. 2b shows a lateral view of the surgical connection device of FIG.1c connected to first and second rods, the rods being anchored tovertebrae via pedicle screws;

FIG. 3a shows a cross-sectional view of the surgical connection devicealong line A-A of FIG. 1 b;

FIG. 3b shows a cross-sectional view of a surgical connection deviceaccording to an alternative embodiment of the present disclosure;

FIG. 4a shows a lateral view of a connection arrangement for connectinga compression arm of a surgical connection device according to anembodiment of the present disclosure to a rod;

FIG. 4b shows a transverse view of the connection arrangement of FIG. 4a;

FIG. 5a shows a transverse view of a connection arrangement forconnecting a traction arm of a surgical connection device according toan embodiment of the present disclosure to a rod;

FIG. 5b shows a transverse view of the connection arrangement of FIG. 5awith a locking piece thereof moved vertically;

FIG. 6 shows a flow chart indicating steps carried out to connect theconnection device to first and second rods according to an embodiment ofthe present disclosure;

FIG. 7 shows a lateral view of a surgical connection device according toanother embodiment of the present disclosure connected to pediclescrews;

FIG. 8 shows a perspective view of the surgical connection device ofFIG. 1c with a modified stabilization member;

FIG. 9 shows a perspective view of the surgical connection device ofFIG. 1c with an additional support

FIG. 10 shows a cross-sectional view of the surgical connection deviceof FIG. 9 along line C-C of FIG. 9;

FIG. 11 shows a perspective view of a surgical connection deviceaccording to another embodiment of the present disclosure;

FIG. 12 shows a perspective view of a surgical connection deviceaccording to yet another embodiment of the present disclosure;

FIG. 13 shows a perspective view of a surgical connection deviceaccording to another embodiment of the present disclosure;

FIGS. 14a and 14b show perspective view of arms usable in surgicalconnection devices according to embodiments of the present disclosure;

FIG. 15 shows a lateral view of a surgical connection device accordingto another embodiment of the present disclosure;

FIG. 16 shows a posterior view of a surgical connection device accordingto yet another embodiment of the present disclosure

FIG. 17 shows a posterior view of a surgical connection device accordingto another embodiment of the present disclosure;

FIG. 18 shows a posterior view of a surgical connection device accordingto yet another embodiment of the present disclosure;

FIGS. 19a and 19b show posterior views of a portion of the surgicalconnection device of FIG. 18 connected to a vertebra prior to and afterspinal growth, respectively;

FIGS. 20a and 20b show lateral views of a portion of the surgicalconnection device of FIG. 18 connected to a vertebra prior to and afterspinal growth, respectively;

FIG. 21 shows a posterior view of a surgical connection device accordingto yet another embodiment of the present disclosure; and

FIGS. 22a and 22b show lateral views of a portion of the surgicalconnection device of FIG. 21 connected to a vertebra prior to and afterspinal growth, respectively.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure relate to posterior spinalsurgery, including spinal fixation surgery, used in the treatment ofspinal conditions such as spondylolisthesis, scoliosis, spinal trauma,spinal tumor and other spinal deformities or degenerative conditions.The surgery can involve inserting pedicle screws into vertebrae toestablish anchor points. A stabilizing rod can then be secured betweenseveral of the anchor points to restrict or limit relative movementbetween vertebrae. This process can be carried out on opposite sides ofthe spine such that first and second rods are in place. When theposterior spinal surgery is completed, spinal fusion may be carried outthrough bone grafting and other means.

Embodiments of the present disclosure also relate to motion preservationdevices, e.g. for use in conjunction with a. mobile disc replacement orotherwise. In general, where bone fusion is carried out, articulation ofthe spine is substantially eliminated. Surgical connection devicesaccording to embodiments of the present disclosure may be used as anadjunct to fusion, e.g., to provide motion preserving support tovertebrae located to one or both sides of a section of fused vertebrae,or to be used in place of a spinal fusion. In either case, the surgicalconnection device may provide for a stabilisation region of the spinewhile enabling motion preservation at or adjacent the stabilised region.

Perspective views of a surgical connection device 100 according to anembodiment of the present disclosure are provided in FIGS. 1a to 1c .The connection device 100 includes an elongate stabilization member 110including a superior end 111 and an inferior end 112 and walls extendingbetween the superior end 111 and the inferior end 112, including a firstwall 113 and second wall 114. First and second compression arms 120, 130extend on substantially opposite sides of the stabilization member 110to connect the stabilization member 110 to first and second rods 210,220, generally as represented in FIG. 1 b. With reference also to FIG.2a (which shows the first rod 210 only), the first and second rods 210,220 are fixed to anchor points, in particular to heads 231 of pediclescrews 230, implanted in vertebrae 240.

The connection device 100 has a cruciform structure, with the axis ofelongation of the stabilization member 110 configured to liesubstantially parallel to the spinal axis and to the axes of elongationof the first and second rods 210, 220 when implanted.

Referring to FIG. 1 b, the first compression arm 120 has a first end 121that is connected to the stabilization member 110 and a second end 122that is connected to the first rod 210. Similarly, the secondcompression arm 130 has a first end 131 that is connected to thestabilization member 110 and a second end 132 that is connected to thesecond rod 220. In this embodiment, the first ends 121, 131 of thecompression arms 120, 130 are permanently fixed to the stabilizationmember 110 (e.g. through integral forming or otherwise). In alternativeembodiments, the connection arms 120, 130 may be connected to thestabilization member 110 during use, e.g. by a surgeon.

The first and second compression arms 120, 130 each extend bothanteriorly and laterally from the stabilization member 110. Thus, whenconnected to the first and second rods 210, 220, the stabilizationmember 110 locates posteriorly and medially of each of the first andsecond rods 210, 220. A cross-sectional view of the device 100 alongline A-A of FIG. 1 b, i.e. in a transverse plane of the device 100extending through the first and second compression arms 120, 130. isprovided in FIG. 3a . The cross-section can be considered substantiallyv-shaped or u-shaped.

Referring to FIGS. 1c and 2 b, after the compression arms 120, 130 areconnected to the first and second rods 210, 220, two pairs of tractionarms are connected between the stabilization member 110 and the rods210, 220. In particular, a pair of first traction arms 141 a, 141 b isconnected between the stabilization member 110 and the first rod 210 anda pair of second traction arms 142 a, 142 b is connected between thestabilization member and the second rod 220. Each of the traction armshas a first end connected to the stabilization member 110 and a secondend connected to the respective rod 210, 220. In an alternativeembodiment, adjacent traction arms, e.g. a first traction arm 141 a anda second traction arm 142 a, or a first traction arm 141 b and a secondtraction arm 142 b, may be joined to form a v-shaped or u-shapedelement, with the apex of the v- or u-shape being secured to thestabilization member 110.

The pair of first traction arms 141 a, 141 b are connected to the firstrod 210 at positions on either side of the position at which the firstcompression arm 120 is connected to the first rod 210. In particular,one of the first traction arms 141 a is connected to the first rod 210at a position that is superior to the position at which the firstcompression arm 120 connects to the first rod 210 and the other firsttraction arm 141 b is connected to the first rod 210 at a position thatis inferior to the position at which the first compression arm 120connects to the first rod 210. Similarly, the pair of second tractionarms 142 a, 142 b are connected to the second rod 220 at positions oneither side of the position at which the second compression arm 130connects to the second rod 220. In particular, one of the secondtraction arms 142 a is connected to the second rod 220 at a positionthat is superior to the position at which the second compression arm 130is connected to the second rod 220 and the other second traction arm 142b is connected to the second rod 220 at a position that is inferior tothe position at which the second compression arm 130 connects to thesecond rod 220.

The traction arms 141 a, 141 b, 142 a, 142 b are connected to thestabilization member 110 via slots 115 provided in the stabilizationmember 110. In this embodiment, the traction arms 141 a, 141 b, 142 a,142 b generally have a fixed angle to the rods 210, 220 and can be slidalong a respective one of the slots 115 to be connected to thestabilization member 110 at an appropriate location.

When the device 100 is implanted, the first compression arm 141 aextends from the stabilization member 110 in an anterior-lateral(right)direction towards the first rod 210, the second compression arm extendsfrom the stabilization member 110 in an anterior-lateral(left) directiontowards the second rod 220; one of the pair of first traction arms 141 aextends from the stabilization member 110 in ananterior-lateral(right)-superior direction towards the first rod 210,the other one of the pair of first traction arms 141 b extends from thestabilization member 110 in an anterior-lateral(right)-inferiordirection towards the first rod 210, one of the pair of second tractionarms 142 a extends from the stabilization member 110 in ananterior-lateral(left)- superior direction towards the second rod 220,and the other one of the pair of second traction arms 142 b extends fromthe stabilization member 110 in an anterior-lateral(left)-inferiordirection towards the second rod 220.

The two pairs of traction arms 141 a, 141 b, 142 a, 142 b are placedunder tension between the stabilization member 110 and the first andsecond rods 210, 220, resulting in superior and inferior portions ofeach of the first and second rods 210, 220 being pulled towards thestabilization member 110 while the first and second compression members120, 130 maintain an intermediate portion of each of the first andsecond rods 210, 220, located between the superior and inferiorportions, at a substantially fixed distance away from the stabilizationmember 110. The controlled application of tensile forces and compressiveforces to different portions of the first and second rods 210, 220 canstraighten the first and second rods 201, 220, change a direction ofbending of the first and second rods 210, 220 or increase a degree ofbending of the first and second rods 210, 220. Bending of the first rod210, following connection of the traction arms 141 a, 141 b, 142 a, 142b, is illustrated in FIG. 2b . As can be seen, superior and inferiorportions 211, 212 of the first rod 210 have been bent posteriorly, incomparison to their positions as shown in FIG. 2a , whereas anintermediate portion 213 of the first rod has remained in asubstantially fixed position. In this example, the rod 210 has beendrawn into lordosis or further lordosis. Where a kyphotic deformity orcorrection is desired the positions of the compression and traction armsmay be reversed. Compression arms may be located. to outer sides of thestabilization device and traction arms may take the intermediateposition.

A flow chart 1000 indicating steps carried out to connect the connectiondevice 100 to the first and second rods is provided in FIG. 6. At step1001, compression arms are connected between the stabilization memberand the first and second rods. At step 1002, traction arms are connectedbetween stabilization member and first and second rods such that thetraction arms are placed in a state of tension and the compression armsare placed. in a state of compression.

The device 100 can be manufactured in a variety of different shapes andsizes, e.g., for use with spines of differing sizes or for use at spinalportions that have or have not been subjected to a laminectomy.Referring to FIG. 3a , the distance Di by which second ends 122, 132 ofthe compression arms 120, 130 are separated in a transverse directioncan be modified to enable use of the device 100 with differently-spacedfirst and second rods 210, 220. Further, the distance D₂ by which thestabilization member 110 is set back posteriorly from the first andsecond rods 210, 220 can be modified in accordance with the size orconfiguration of the spine. The distances Di, D₂ may be modified duringmanufacture of the device 100 and/or may be adjustable during use of thedevice, e.g. through manual bending of the compression arms 120, 130 orotherwise. In general, depending on the size of the spine, the devicemay be configured such that the stabilization member is positioned about5-25 mm or 5-35 mm or 10-35 mm posteriorly of a plane extending throughthe rods or otherwise.

The stabilization member may therefore provide a third elongatestiffening element, e.g. a form of third rod, which is posteriorlylocated relative to the first and second rods. By positioning thestabilization member posteriorly of the first and second rods, andthrough the provision of both traction and compression arms, a surgeonmay be provided with a significantly increased ability to control theapplication of forces applied to vertebrae via the first and second rodsfor the purpose of re-alignment and/or stabilization of the vertebrae.Substantial forces may be applied to the rods via the arms in anydirection in three-dimensional space. The forces may be transmitted tovertebrae by pedicle screws attached to the rods, without pulling outthe screws or breaking the pedicle. There may be provided reinforcing ofthe rod/screw construct in all planes to resist or modulate deformingloads applied to the construct during weight bearing, e.g., prior to thefusion of the spine. The devices and apparatus may assist in theapplication of forces to adjacent segments of the rod/screw construct,e.g. sections defined between immediately adjacent pedicle screws orbetween a plurality of pedicle screws. The devices and apparatus maybuffer against undesirable distortion at an end of the construct forexample, while maintaining e.g., a lordotic or kyphotic bias, forexample. These forces may be applied off-spinal-axis where a slightenduring scoliosis is encountered. The devices and apparatus may providefor a triangular-cross section of reinforcement and may provide means ofshaping rods in situ.

While the device 100, e.g., as illustrated in FIG. 3a , is arranged tobe substantially symmetrical about the mid-sagittal plane 250, inalternative embodiments the device 100 may be asymmetrically arrangedabout the mid-sagittal plane 250. For example, as shown in FIG. 3b , thestabilization member 110 may be positioned laterally of the mid-sagittalplane 250. To achieve this, one of first and second compression arms120′, 130′ may be longer than the other of the first and secondcompression arms 120′, 130′. This off-axis or eccentric positioning ofthe stabilization member 110 can enable the stabilization member 110 tolocate laterally of the tips of the spinous processes, making the devicemore suitable for positioning over vertebrae that have not beensubjected to a laminectomy. It can also enable the device to handleapplication of more complex forces, e.g. associated with scolioticspines, or in children with growing spines.

In an alternative embodiment, to enable the connection device to be usedin conjunction with vertebrae that have not been subjected to alaminectomy, while positioning the stabilization member on themid-sagittal plane, the stabilization member may comprise a centralopening to receive one or more spinous processes. For example, withreference to FIG. 8, a connection device 101 according to an embodimentof the present disclosure may be configured substantially in accordancewith the connection device 100 described with respect to precedingembodiments, but the stabilization member 110′ may comprise first andsecond stabilizing rods 1101, 1102 that each extend along the spine andwhich are spaced apart in a medial-lateral direction such as to providea gap 1103 to accommodate tips of the spinous processes. Connectors1104, 1105 connect the two stabilizing rods 1101, 1102 together. Theconnectors are configured to extend through interspinous spaces betweenadjacent spinous processes, without obstruction to the spinousprocesses. In alternative embodiments, connectors 1104, 1105 mayadditionally or alternatively extend through an interspinous ligamentand/or through a spinous process or any other structure located betweenthe stabilizing rods 1101, 1102.

Referring again to FIGS. 1a to 1 c, while the first ends 121, 131 of thecompression arms 120, 130 in the device 100 are fixed in positionrelative to the stabilization member 110, in alternative embodiments theconnection positions of the first ends of the compression arms may beadjustable relative to the stabilization member. For example, the firstends of the compression arms may be fixed to the stabilization membervia a sleeve that is slidable along the stabilization member. By slidingthe sleeve along the stabilization member, the positions at which thefirst and second compression arms extend from the stabilization membercan be adjusted along the spinal axis, enabling the compression arms tobetter position between anatomical features, and/or force to be appliedvia the compression arms at more desirable positions of the rods. Whendesired positions are achieved, the sleeve can be fixed to thestabilization member, e.g., using a locking screw.

The second ends 122, 132 of the compression arms 120, 130 may beconnected to the respective rods 210, 220 via a connection element suchas an integral or separately formed sleeve or foot-piece, which isclamped to the rod 210, 220. If the rods 210, 220 are not parallel, asis often the case, the compression arms 120, 130 may be bent manually toaccommodate this non-parallel rod alignment without weakening theirresistance to compression. Example foot-pieces 123, 133, which mount tothe rods 210, 220, are illustrated in FIGS. 3a and 3b , for example,which foot pieces 123, 133 each have an engagement surface that contactsa posterior surface of the rod around approximately 180 degrees of therod circumference.

To provide for increasingly secure engagement between the compressionarms 120, 130 and the rods 210, 220, a connection arrangement may beprovided as illustrated in FIGS. 4a and 4b , for example. At the secondend 122 of the compression arm 120, the compression arm 120 has a curvedabutment surface 124 for engaging a posterior surface of the rod 210. Alock unit 125 is provided, including a pair of capture legs 1251, 1252having hooked distal ends 1253, 1254, the capture legs 1251, 1252depending from opposite sides of a cross beam 1255. The hooked distalends 1253, 1254 hook onto anterior surfaces of the rod 120 on eitherside of the compression arm 120, via medial and lateral sides,respectively, of the rod 210. The curved abutment surface 124 of thecompression arm 120 and the hooked distal ends 1253, 1254 of the capturelegs 1251, 1252 are drawn towards each other, such as to clamp to eitherside of the rod 210, through tightening of a locking screw 1256 thatextends through the cross beam 1245 of the locking unit 124 and whichhas an abutment 1257 that presses the second end 122 of the compressionarm 120 towards the rod 210.

The second ends of the traction arms 141 a, 141 b, 142 a, 142 b may beconnected to the respective rods 210, 220 via hook elements 141 1, asindicated very generally in FIGS. 1c and 2b , which hook elements 1411hook underneath anterior surfaces of the rods 210, 220.

To provide for increasingly secure engagement between the traction arms141 a, 141 b, 142 a, 142 b and the rods 210, 220, a locking piece 143can be provided as illustrated in FIGS. 5a and 5b , for example. Thelocking piece 143 has a curved abutment surface 1431 that is forced downon a posterior surface of the respective rod 210 such that the rod isclamped between the locking piece 143 and the hook element 141 1. Thelocking piece 143 is secured to the traction arm 141 a via a screw 144that extends both through the locking piece 143 and the traction arm 141a, and which screw 141 a can be tightened to increase the clampingforce.

The screw 144 also provides a pivot for the locking piece 143, aroundwhich the locking piece 143 can rotate relative to the traction arm 141a. When the screw 144 is in a loosened stated, the locking piece 143 canpivot away from the hook element 141 1 to a storage position asillustrated in FIG. 5b , providing a clear access path for the rod 210to move towards and engage the hook element 141 1. The locking piece 144includes a recessed section 1432. to snap-fit with the traction arm 141a when in the storage position, maintain the locking piece 143 in thestorage position prior to clamping.

In connection devices according to embodiments of the presentdisclosure, the stabilization member can have the added benefit ofproviding a guiding or reattachment surface for spinal musculature andfascia after surgery, allowing better wound closure and care. It mayallow the musculature to lie in a more anatomic post-operative plane andhence may decrease post-operative pain/stiffness. It may improvepost-operative muscular power and function and provide for moreefficient energy utilization of these muscles to residualun-instrumented levels. Additionally, the stabilization member and/orother parts of the device, may be used as a support for further dynamicconnectors between instrumented vertebrae allowing controlled yetflexible deformity correction superior to and/or inferior to the fusedsection. Furthermore, the device may act as a scaffold for increasedbone graft attachment points and hence greater fusion mass.

In a further embodiment of the present disclosure, as illustrated inFIG. 7, the connection device 100 is adapted for use with a spine thathas no first and second rods 210, 220 attached to pedicle screws 230. Inthis instance, the compression and traction arms 120, 130, 141 a, 141 b,142 a, 142 b are connected directly to the heads 231 of the pediclescrews 230. Transverse or longitudinal stiffening members 140 a, 140 bare optionally provided between the traction and compression arms, in avariety of arrangements, to create a stiffer construct for stabilisingthe spine to lead to fusion.

In a further variation, a combination of traction and compression armsmay be employed with or without further stiffening additions, to retaina kyphotic, lordotic and rotational stiffness, yet allow longitudinaldisplacement of the pedicle screws (or other vertebral securing means)with respect to each other, as is desirable to occur with growing,younger scoliotic patients. By this expedient approach, repeatedsurgeries or stunting of growth may be obviated while still correctingthe deformity of scoliosis in younger patients. The longitudinal “play”in the arms can be achieved by uniaxial pliability in their formedshape, such as can be generated by a single plane of spring formingwithin the material and stiffening cross members for rotationalstability.

With reference to FIGS. 9 and 10, in one embodiment of the presentdisclosure the surgical connection device 100 further comprises asupport 30 for supporting the stabilization member 110 from an anteriorside. The support 30 functions as a prop for the stabilization member110, helping maintain the stabilization member 110 in a posteriorlylocated position. The support 30 has first connector, in particular across-bar 31 that connects between the first and second rods 210, 220 onopposite lateral sides of the spine, and a second connector, inparticular a buttress 32 that connects between the cross-bar 31 and ananterior surface 1106 of the stabilization member 110,

The cross-bar 31 and buttress 32 can be integrally formed or can beseparate pieces that are assembled during surgery, e.g. by beingsnap-fit to each other and/or to the stabilization member 110 and firstand second rods 210, 220. The cross-bar 31 and buttress 32 are eachelongate, with their directions of elongation extending substantiallyperpendicularly to each other. The cross-bar 31 extends in amedial-lateral direction and the buttress 32 extends in ananterior-posterior direction, providing in combination a generallyT-shaped support 30.

A support configured in a similar manner to the support 30 describedabove can be used in conjunction with other types of surgical connectiondevices according to embodiments of the present disclosure. In oneembodiment, with reference to FIG. 11, a surgical connection device 40is used to provide stabilization at a section of the spine where firstand second rods 210, 220 are again connected to a plurality of first andsecond anchor points 230. The connection device 40 includes an archedrod 41 connected diagonally between a first anchor point 230 a implantedin a first vertebra 241 and a second anchor point 230 b implanted in asecond vertebra 242, the first and second anchor points 230 a, 230 bbeing positioned substantially on opposite lateral sides of the spine. Asupport 300 is provided that again has a cross-bar 301 that connectsbetween the first and second rods 210, 220 on opposite lateral sides ofthe spine and a buttress 302 that connects between the cross-bar 31 andan anterior surface of the arched rod 41 such as to maintain thecurvature of the arched rod 41 and/or provide an increased tension inthe arched rod 41. The buttress 302 includes a contact piece 303 toconnect to the arched rod 41. The arched rod 41 may induce asymmetriccorrective movement in the spine or otherwise.

With reference to FIG. 12, in another embodiment, the arched rod 41 isused to stabilize a spinal section that has no first and second rodsconnected on opposite lateral sides of the spine. In this embodiment,the cross-bar 301 of the support 300 is connected directly betweenanchor points 231 a, 231 b, rather than rods.

With reference to FIG. 13, in yet another embodiment, two arched rodsare provided, including a first arched rod 42 and second arched rod 43.The first arched rod 42 is connected diagonally between a first anchorpoint 230 a implanted in a first vertebra 241 and a second anchor point230 b implanted in a second vertebra 242. The second arched rod 43 isconnected diagonally between a third anchor point 230 c implanted in thefirst vertebra 241 and a fourth anchor point 230 d implanted in thesecond vertebra 242. The first and fourth anchor points 230 a, 230 d arepositioned on substantially opposite lateral sides of the spine to thesecond and third anchor points 230 b, 230 d. The first and second archedrods 42, 43 cross each other. Substantially at the position at which thefirst and second arched rods 42, 43 cross each other, the support 300 isprovided, the support including a cross-bar 301 and a buttress 302substantially as described above with reference to FIG. 11, but with amodified contact piece 304 to enable the buttress to connect to anteriorsurfaces of both arched rods 42, 43. The support 300 may maintaincurvature of the two arched rods 42, 43 and/or provide increased tensionin the arched rods 42, 43. The arched rod 42, 43 may induce asymmetricor symmetric corrective movement in the spine, depending on whether ornot different tensile forces are applied across each rod 42, 43.

Diagonally extending arched rods 41, 42, 43, connected to substantiallystraight first and second rods 210, 220, are described above withreference to FIGS. 11 to 13. However, in alternative embodiments,diagonally extending rods that are substantially straight may beprovided, which are optionally connected to arched first and secondrods. In general, the diagonally extending rods may have a variety ofdifferent shapes. They may be in the form of a spring, e.g., a helicalspring, or they may have sinuosity such as an s-shape.

In any of the embodiments disclosed herein, the surgical connectiondevice may modify the stiffness of the spine at different positions ofthe spine, e.g. at different vertebral levels, to different degrees. Thestiffness may be may be modified through the provision of a stabilizingmember with varying stiffness over its length, and/or through theprovision of arms connecting the stabilizing member to rods or anchorpoints that have differing stiffness properties. The stiffness may beselected depending on the degree of motion preservation required and thelocation of the required motion preservation. The stabilization memberand/or arms may vary in stiffness through material selection, diametersand/or shape including sinuosity, e.g. flexible s-bends.

The stabilization member and/or arms may have varying flexibility acrossdifferent planes. For example, they may have omni-directionalflexibility, bi-directional flexibility, or uni-directional flexibility.The stabilization member and/or arms with omni-direction flexibility mayhave uniform flexibility in every plane or different flexibility indifferent planes. Directional variation in flexibility may be achievedthrough shaping of the stabilization member and/or arms. For example,any one of the arms may be have a plate-like configuration similar tothe arm 146 illustrated in FIG. 14a , such that they are more flexiblein one plane than another plane, or have a circular cross-sectionsimilar to the arm 147 illustrated in FIG. 14b , such that they have thesame flexibility in any direction.

In any of the embodiments, one or more of the arms may includeresorbable elements such as resorbable collars that serve to stiffen thearms, but which are gradually resorbed within the body such that theirstiffening effect gradually reduces over time. Thus, any one or morearms may have a flexibility that changes over time. This can beadvantageous where increased stiffening and stabilization is requiredimmediately post-implantation, to ensure appropriate patient recovery,but where increased flexibility and motion preservation is desirablethereafter.

An example of a surgical connection device 50 including arms withresorbable elements according to an embodiment of the present disclosureis illustrated in FIG. 15. Generally, the surgical connection device 50is designed to provide a motion preservation function, and in thisinstance is used in conjunction with a mobile disc replacement toprovide motion preserving posterior support to a replacement disc 500.The connection device 50 includes a stabilization member 51 and aplurality of arms 52 a-d that connect between the stabilization memberand anchor points, in particular pedicle screws 230, implanted invertebrae 240 a-d located either side of the replacement disc 500 and onopposite lateral sides of the spine (albeit arms on one side of thespine only are represented in FIG. 15). The stabilization member 51locates posteriorly of the pedicle screws 230. A first pair of the arms52 b, 52 c connect to pedicle screws 230 implanted in first superior andinferior vertebrae 240 b, 240 c immediately adjacent the disc 500. Asecond pair of the arms 52 a, 52 d connect to pedicle screws 230implanted in second superior and inferior vertebrae 240 a, 240 d thatare immediately outside the first superior and inferior vertebrae 240 b,240 c. The first pair of arms 52 b, 52 c each have a resorbablestiffening collar 53 mounted thereon, providing for reduced flexibilityand therefore increased stiffness of the arms 52 b, 52 c and thereforethe connection device 50, immediately adjacent the replacement disc 500.The second pair of arms 52 a, 52 d are substantially identical to thefirst pair of arms but have no stiffening collars 53. Accordingly, thesecond pair of arms 52 a, 52 d are more flexible than the first pair ofarms 52 b, 52 c. Immediately after implantation, the connection device50 provides for increased stiffening and stabilization adjacent thereplacement disc 500, while providing greater motion-preservationfunction and outer vertebral levels. However, as the resorbable collars53 are gradually resorbed over time, the first pair of arms 52 b, 52 cexhibit increased flexibility, increasing the motion preservationfunction of the entire connection device 50, when the replacement disc500 is better integrated with the spine.

In another embodiment, as shown in FIG. 16, a surgical connection device60 is provided that is adapted to stabilize a lateral facet joint 243 ofa spine. The lateral facet joint 243 being provided between an L4vertebra 244 and an L5 vertebra 245 in this embodiment, although theconnection device 60 may be used with alternative vertebrae. Theconnection device 60 includes a stabilization member 61 and a pluralityof arms 62, 63, including a pair of first arms 61 and a pair of secondarms 62. The first arms 62 are connected to anchor points, in particularpedicle screws 230, on respective lateral sides of the L4 vertebra 244and the second arms are connected to anchor points, in particularpedicle screws 230, on respective lateral sides of the L5 vertebra 245.The stabilization member 61 is elongate along the spinal axis. Thestabilization member 61 is significantly stiffer than the arms 62, 63.The flexibility of each arm 62, 63 is independently selected to allowdesired stabilisation and motion preservation. The arms 62, 63 extendmedially and posteriorly from their connection points with the screws230 such that the stabilization member 61 is again positionedposteriorly of the pedicle screws 230, and above the left and right L4nerves. A partial laminectomy of the spinous processes of the L4 and L5vertebrae 244, 245 has been carried out to allow the stabilizationmember 61 to be positioned in the desired location.

With reference to FIG. 17, in one embodiment a surgical connectiondevice 70 is provided including a stabilization member 71 with aplurality of arms 72, 73. A first portion of the stabilization member 71is connected to first and second rods 210, 220 of a first spinal portionby first arms 72. Second and third portions of the stabilization member71, located either side of the first portion, are connected directly toanchor points 240 of second and third spinal portions by second arms 73.The first spinal portion includes three fused vertebra 2301, 2302, 2303.The second and third spinal portions are located either side of thefirst spinal portions and include non-fused vertebra 2304, 2305. In thisembodiment, the arms 73 connecting the stabilization member 71 to thenon-fused vertebrae 2304, 2305 have greater flexibility than the arms 72connecting the stabilization member to the fused vertebrae 2301, 2302,2303. Use of stiffer arms 72 at the fused vertebrae provides greaterstability to the overall surgical connection device and rod constructwithout providing any adverse effect to overall motion preservation.However, the more flexible arms 73 connected to anchor points atnon-fused vertebrae provide increased motion preserving stabilisationwhile decreasing the tendency for degeneration in those vertebrallevels.

With reference to FIG. 18, in another embodiment of the presentdisclosure a surgical connection device 80 is provided including astabilization member 81 and a plurality of arms 82, 83. A first portion811 of the stabilization member 81 is connected to first and second rods210, 220 of a first spinal portion of a scoliotic spine by anchor arms82. A second portion 812 of the stabilization member 81, locatedsuperiorly of the first portion 811 of the stabilization member 81 inthis embodiment, is connected directly to a second spinal portion by afirst control arm 83. The first spinal portion includes three fusedvertebra 2301, 2302, 2303. The second spinal portion is locatedsuperiorly of the first spinal portion and includes a non-fused vertebra2306.

The first control arm 83 is adapted to control a movement of the secondportion of the spine, including the non-fused superior vertebrae 2306,relative to the stabilization member 81. At the second portion 812 ofthe stabilization member 81, the stabilization member 81 locates at aposition that is medial to a first lateral edge 2307 of the vertebra2306. The first control arm 83 projects outwardly from the secondportion 812 of the stabilization member in a direction towards the firstlateral edge 2307.

The first control arm 83 is rotatable relative to the second portion 812of the stabilization member 81 and rotatable relative to the vertebra2306. Rotation is achieved through the provision of articulated joints831 between the first control arm 83 and stabilization member 81 andbetween the first control arm 83 and the vertebra 2306.

The first control arm 83 is substantially rigid such as to maintain afixed length while permitting movement between the vertebra 2306 and thestabilization member 81.

A variation of the connection device 80 is illustrated in FIG. 21. Inthis variation, a second control arm 84 is provided in addition to thefirst control arm 83. Like the first control arm 83, the second controlarm 84 is also adapted to control a movement of the second portion ofthe spine, including the non-fused vertebrae 2306, relative to thestabilization member 81. At the second portion 812 of the stabilizationmember 81, the stabilization member 81 locates at a position that isalso medial to a second lateral edge 2308 of the vertebra 2306. Thesecond control arm 84 projects outwardly from the second portion 812 ofthe stabilization member in a direction towards the second lateral edge2308.

The second control arm 84 is also rotatable relative to the secondportion 812 of the stabilization member 81 and rotatable relative to thevertebra 2306. Rotation is again achieved through the provision ofarticulated joints 841 between the second control arm 84 andstabilization member 81 and between the second control arm 84 and thevertebra 2306.

By providing a first control arm 83, or first and second control arms83, 84, which arm(s) control movement of the vertebra 2306 relative tothe stabilization member 81, the surgical connection device 80 canprovide for re-alignment of the scoliotic spine. Where a recipient ofthe surgical connection device is a child, for example, natural movementof the spine may occur as a result of growth of the spinepost-implantation. The growth may be such as to move the vertebra 2306in a direction away from the first portion of the spine including fusedvertebrae 2301, 2302, 2303. However, by connecting the control arm(s) tothe non-fused vertebra 2306, the direction of growth is controlled bythe surgical connection device 80. Relative lengthening of the spineforces the control arm(s) 83, 84 to rotate through an arc in respectiveplanes. The orientation of each plane is selected to drive a desiredcorrection of the tilt and rotation of the scoliotic spine. Assisting inthis process is the anchoring of the stabilization member to the fusedportion of the spine.

When a single, first control arm 83 is employed, the rotation of the arm83 forces lateral and posterior movement of the vertebra 2306, from aposition as represented in FIGS. 19a and 20a to a position asrepresented in FIGS. 19b and 20b . (In FIGS. 19b and 20b , the dottedline indicates the prior positioning of the vertebra 2306 shown in FIGS.19a and 20a , respectively.)

When both a first control arm 83 and a second control arm 84 areemployed, the rotation of the arms 83, 84 forces lateral and posteriormovement of the vertebra 2306 along with rotation of the vertebra aboutthe spinal axis, from a position as represented in FIG. 22a to aposition as represented in FIG. 22b , (In FIG. 22b the dotted lineindicates the prior positioning of the vertebra 2306 shown in FIG. 22a.)

The surgical connection device 80, while not restricting growth of thespine, may therefore force a straightening or other type of shapeadjustment of the spine during growth of the spine. This can beparticularly advantageous to treat scoliosis of the spine in children,although the connection device is not necessarily limited to such use.By taking the approach disclosed, growth of the spinal column may not beretarded, the need for re-operation to allow growth may he obviated orat least reduced, and correction of the spine can be achievedpost-operatively and in a gradual fashion.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the above-describedembodiments, without departing from the broad general scope of thepresent disclosure.

For example, while the device illustrated in some of the Figures isprovided with compression arms projecting across a single transverseplane only, in other embodiments, compression arms may project overdifferent transverse planes or in other directions. Two pairs of firstand second compression arms may be provided, for example, located atdifferent positions along the axis of elongation of the stabilizationmember.

As another example, in any one of the embodiments further arms of rodsmay be connected to the arms, e.g., the traction or compression arms, ina longitudinally arranged manner. This may further stabilise theconstruct and provide further stiffening or induction of tension. Thefurther arms or rods may run substantially parallel to the first andsecond rods and to the stabilisation device, for a portion or whole ofthe construct. This may be particularly advantageous where the first andsecond rods (connected between the anchor points) are excluded, in orderto increase rigidity of the construct.

As yet another example, the device may comprise additional arms that areconnectable to the stabilisation member where longer constructs aredesired. For example, first and second compression arms may be integralto the system, but for longer constructs further compression arms may bealso be included or selectively introduced by the surgeon.

The present embodiments are, therefore, to be considered in all respectsas illustrative and not restrictive.

1. A surgical connection device for a spine, a plurality of first anchorpoints being fixed to vertebrae at a first lateral side of the spine, aplurality of second anchor points being fixed to vertebrae at a secondlateral side of the spine, a first spinal rod being attached to theplurality of first anchor points and a second spinal rod being attachedto the plurality of second anchor points, the device comprising: astabilization member; a plurality of compression arms to connect thestabilization member to the first and second rods and bear compressiveforces between the stabilization member and the first and second rods;and a plurality of traction arms to connect the stabilization member tothe first and second rods and bear tensile forces between thestabilization member and the first and second rods.
 2. The surgicalconnection device of claim 1, wherein the stabilization member iselongate.
 3. The surgical connection device of claim 2, wherein thestabilization provides a third spinal rod that is configured to extendsubstantially parallel to the first and second rods.
 4. The surgicalconnection device of any one of the preceding claims, wherein theplurality of compression arms comprise at least a first compression armto connect between the stabilization member and the first rod and atleast a second compression arm to connect between the stabilizationmember and the second rod.
 5. The surgical connection device of claim 4,wherein the plurality of traction arms comprise at least two firsttraction arms to connect between the stabilization member and the firstrod.
 6. The surgical connection device of claim 5, wherein the two firsttraction arms connect to the first rod at positions on either side ofthe position at which the first compression arm connects to the firstrod.
 7. The surgical connection device of claim 5 or 6, wherein theplurality of traction arms comprise at least two second traction arms toconnect between the stabilization member and the second rod.
 8. Thesurgical connection device of claim 8, wherein the two second tractionarms connect to the second rod at positions on either side of theposition at which the second compression arm connects to the second rod.9. The surgical connection device of any one of the preceding claims,wherein the connection positions of the compression arms to thestabilization member and/or the connection positions of the compressionarms to the rods are variable along an axis of elongation of thestabilization member and rods.
 10. The surgical connection device of anyone of the preceding claims, wherein the connection positions of thetraction arms to the stabilization member and/or the connectionpositions of the traction arms to the rods are variable along an axis ofelongation of the stabilization member and rods.
 11. The surgicalconnection device of any one of the preceding claims, wherein thecompression arms are able to withstand substantially higher compressiveforces than the traction arms.
 12. The surgical connection device of anyone of the preceding claims, wherein the traction arms are more flexiblethan the compression arms.
 13. The surgical connection device of any oneof the preceding claims, wherein the compression arms extend from thestabilization member in an anterior-lateral direction.
 14. The surgicalconnection device of any one of the preceding claims, wherein a firstone of the compression arms extends from the stabilization member in ananterior-lateral direction towards the first rod; a second one of thecompression arms extends from the stabilization member in ananterior-lateral direction towards the second rod; one of the tractionarms extends from the stabilization member in ananterior-lateral-superior direction from the stabilization membertowards the first rod; another of the traction arms extends from thestabilization member in an anterior-lateral-inferior direction from thestabilization member towards the first rod; another of the traction armsextends from the stabilization member in an anterior-lateral-superiordirection from the stabilization member towards the second rod; andanother of the traction arms extends from the stabilization member in ananterior-lateral-inferior direction from the stabilization membertowards the second rod.
 15. The connection device of any one of thepreceding claims, wherein the stabilization member is configured tolocate medially and posteriorly of the first and second rods,
 16. Theconnection device of any one of the preceding claims, wherein when thestabilization member is connected to the first and second rods by thearms, the direction of elongation of the stabilization member liessubstantially parallel to the axis, or desired axis, of the spine andthe stabilization member locates: (a) posteriorly of the rods at aposition that is not substantially more posterior than the posteriorextents of the tips of spinous processes of the vertebrae to which theanchor points are fixed; or (b) when one or more spinous processes ofthe vertebrae to which the anchor points are fixed have been removed,posteriorly of the rods at a position that is not substantially moreposterior than the positions at which the posterior extents of the tipsof the spinous processes of the vertebrae to which the anchor points arefixed were located prior to removal.
 17. A surgical connection devicefor a spine, a plurality of first anchor points being fixed to vertebraeat a first lateral side of the spine and a plurality of second anchorpoints being fixed to vertebrae at a second lateral side of the spine,the device comprising: a stabilization member; a plurality ofcompression arms to connect the stabilization member to at least onefirst anchor point and at least one second anchor point and bearcompressive forces between the stabilization member and the first andsecond anchor points; and a plurality of traction arms to connect thestabilization member to at least one first anchor point and at least onesecond anchor point and bear tensile forces between the stabilizationmember and the first and second anchor points.
 18. A surgical method fora spine, a plurality of first anchor points being fixed to vertebrae ata first lateral side of the spine, a plurality of second anchor pointsbeing fixed to vertebrae at a second lateral side of the spine, a firstspinal rod being attached to the plurality of first anchor points and asecond spinal rod being attached to the plurality of second anchorpoints, the method comprising: connecting a stabilization member of asurgical connection device to the first and second rods using aplurality of compression arms that are configured to bear compressiveforces between the stabilization member and the rods; and connecting aplurality of traction arms of the surgical connection device between thestabilization member and the first and second rods, the traction armsbeing configured to bear tensile forces between the stabilization memberand the rods.
 19. A surgical method for a spine, a plurality of firstanchor points being fixed to vertebrae at a first lateral side of thespine and a plurality of second anchor points being fixed to vertebraeat a second lateral side of the spine, the method comprising: connectinga stabilization member of a surgical connection device to at least onefirst anchor point and at least one second anchor point using aplurality of compression arms that are configured to bear compressiveforces between the stabilization member and the first and second anchorpoints; and connecting a plurality of traction arms of the surgicalconnection device between the stabilization member and at least onefirst anchor point and at least one second anchor point, the tractionarms being configured to bear tensile forces between the stabilizationmember and the first and second anchor points.